1. Field of the Invention
The present invention relates to a wafer process body, a wafer processing member, and a wafer processing temporary adhesive material, which is capable of giving a thin wafer effectively, respectively, and a method for manufacturing a thin wafer.
2. Description of the Related Art
A three-dimensional semiconductor mount becomes indispensable to realize higher density, larger capacity, higher processing speed, and lower power consumption than ever. According to the three-dimensional semiconductor mounting technology, a semiconductor chip is made thin, and then this is stacked in multilayer while connecting them by a silicon through electrode (TSV: through silicon via). To realize this, a process to make a substrate formed with a semiconductor circuit thin by grinding a surface not formed with a circuit (also referred to as the “back surface”) and a process to form an electrode including TSV on the back surface thereafter are necessary.
In the process of grinding the back surface of the silicon substrate in the past, a protection tape is attached on the other side of the grinding surface to avoid wafer breakage during the time of grinding. However, because this tape uses an organic resin film as its base, strength and heat resistance thereof is insufficient though flexible; and thus, this is not suitable for the TSV forming process and for the process of forming a wiring layer on the back surface.
Accordingly, a proposal is made as to the system wherein a semiconductor substrate is bonded to a supporting body such as silicon and glass via an adhesive layer thereby making it withstand to the processes of back surface grinding and formation of a TSV and a back surface electrode. In this process, an adhesive layer to bond a substrate with a supporting body is important. It is necessary that this adhesive can bond the substrate with the supporting body coherently and has durability to withstand the subsequent processes, and in addition, the thin wafer needs to be readily removed from the supporting body at the end. Because removal is done at the end as mentioned above, this adhesive layer is called as a temporary adhesive layer in this specification.
Until now, following technologies in the public domain have been proposed as to the temporary adhesive layer and the removal method thereof, that is, a technology wherein a high energy beam is irradiated to an adhesive which contains a light-absorbing substance thereby decomposing the adhesive layer to effect removal of the adhesive layer from the supporting body (Patent Document 1) and a technology wherein a thermally meltable hydrocarbon compound is used in the adhesive thereby effecting adhesion and removal in the melting condition by heating (Patent Document 2). However, in the former technology, there have been such problems as: an expensive instrument such as a laser is necessary; a special substrate such as a glass substrate which can transmit a laser beam is necessary for the supporting body; and a treatment time per one substrate is long. In the latter technology, although control can be done easily only by heating, heat stability at high temperature above 200° C. is insufficient; and thus, its application range has been narrow. Moreover, these temporary adhesive layers have not been suitable for formation of a uniform film on a highly non-planar substrate or for coherent adhesion to the supporting body.
Alternatively, a technology in which a silicone agglutinant is used as the temporary adhesive layer is proposed (Patent Document 3). In this technology, a substrate is bonded to a supporting body by using an addition reaction-curable silicone agglutinant; and during the time of removal, the substrate is detached from the supporting body by soaking them in a chemical agent which can dissolve or decompose the silicone resin. This technology requires a very long time for removal; and thus, application to a practical manufacturing process is difficult.